In the book, LeBlanc was asked about his thoughts on the writers they had for the long-running series. LeBlanc praised them as “highly, highly underrated” and said they were some of the best on television. Then he mentioned the prank. LeBlanc said:
“We have this really fun thing that we do with David Crane. He’s super, super smart, but he’s also ultraconservative in that he doesn’t like toilet jokes. So Perry and me, just to egg him on, will pitch toilet humor to him. And we’ll pitch it with a straight face in front of everyone. He doesn’t have any idea we do it on purpose.”
I mean, he probably figured it out after ten years, but I love that they did this. I’m sorry, but toilet humor is pretty funny. The show didn’t have a ton of it, but it was certainly there. This is just a guess, but in season 7, episode 10, there is a scene about holiday decorations, and at the end, Joey just walks out of Monica (Courteney Cox) and Chandler’s bathroom with a newspaper and out the front door, with the implication that he’d been in there the entire time. I’m going to guess that was a pitch from these two.